ASTRONOMY - A Vortex Aurora over Iceland

2022 April 4

A Vortex Aurora over Iceland
Image Credit & Copyright: Christophe Suarez

Explanation: No, the car was not in danger of being vacuumed into space by the big sky vortex. For one reason, the vortex was really an aurora, and since auroras are created by particles striking the Earth from space, they do not create a vacuum. This rapidly developing auroral display was caused by a Coronal Mass Ejection from the Sun that passed by the Earth closely enough to cause a ripple in Earth's magnetosphere. The upper red parts of the aurora occur over 250 kilometers high with its red glow created by atmospheric atomic oxygen directly energized by incoming particles. The lower green parts of the aurora occur over 100 kilometers high with its green glow created by atmospheric atomic oxygen energized indirectly by collisions with first-energized molecular nitrogen. Below 100 kilometers, there is little atomic oxygen, which is why auroras end abruptly. The concentric cylinders depict a dramatic auroral corona as seen from the side. The featured image was created from a single 3-second exposure taken in mid-March over Lake Myvatn in Iceland.

ASTRONOMY - CMB Dipole: Speeding Through the Universe

2022 April 3

CMB Dipole: Speeding Through the Universe
Image Credit: DMR, COBE, NASA, Four-Year Sky Map

Explanation: Our Earth is not at rest. The Earth moves around the Sun. The Sun orbits the center of the Milky Way Galaxy. The Milky Way Galaxy orbits in the Local Group of Galaxies. The Local Group falls toward the Virgo Cluster of Galaxies. But these speeds are less than the speed that all of these objects together move relative to the cosmic microwave background radiation (CMBR). In the featured all-sky map from the COBE satellite in 1993, microwave light in the Earth's direction of motion appears blueshifted and hence hotter, while microwave light on the opposite side of the sky is redshifted and colder. The map indicates that the Local Group moves at about 600 kilometers per second relative to this primordial radiation. This high speed was initially unexpected and its magnitude is still unexplained. Why are we moving so fast? What is out there?

ASTRONOMY - Nova Scotia Northern Lights

 2022 April 2

Nova Scotia Northern Lights
Image Credit & Copyright: Jason Dain

Explanation: This almost otherworldly display of northern lights was captured in clear skies during the early hours of March 31 from 44 degrees north latitude, planet Earth. In a five second exposure the scene looks north from Martinique Beach Provincial Park in Nova Scotia, Canada. Stars of the W-shaped constellation Cassiopeia shine well above the horizon, through the red tint of the higher altitude auroral glow. Auroral activity was anticipated by skywatchers alerted to the possibility of stormy space weather by Sun-staring spacecraft. The predicted geomagnetic storm was sparked as a coronal mass ejection, launched from prolific solar active region 2975, impacted our fair planet's magnetosphere.

PHOTOGRAPHIE - Vénus et la voie lactée

 

Le retour de la voie lactée en 2022. Photos prises à la plage de la Verne à La Seyne sur Mer, devant les pointus.

Technique : Matériel : NIKON Z6 II + Nikkor 24-70 f/4. Empilement de 50 poses : 24 mm - 15 s - f/4 - ISO 800. Traitement : Sequator + Lightroom | Date : 03.02.2022

Auteur : F. Xavier Cuvelier
https://www.photorama.fr

ASTRONOMIE - Rencontre spectaculaire entre Mars et Saturne

 

Les positions respectives des planètes Mars et Saturne entre le 3 et le 7 avril 2022 vers 6h30 (heure de Paris) dans une paire de jumelles de type 10×50, avec un champ de 6 degrés.

Du côté de Mars et de Saturne, un croisement très serré se dessine : au meilleur de l’événement, les deux planètes auront une distance apparente inférieure à 20 minutes d’arc (l’équivalent des deux-tiers du diamètre lunaire) !

La rencontre est spectaculaire et aisément visible à l’œil nu bien que les deux planètes ne soient pas au maximum de leur éclat. Privilégiez simplement de les observer dans un ciel encore suffisamment noir pour les repérer : aux latitudes de la France métropolitaine, il faut donc sortir vers 6h30-6h45. Tournez-vous vers l’horizon est sud-est et repérez l’étincelante Vénus : notre duo se trouve un peu plus à droite, il s’agit de deux points à l’éclat similaire.

Stelvision

ASTRONOMY - Exploring the Antennae

 2022 March 31

Exploring the Antennae
Image Credit & Copyright: Dietmar Hager, Eric Benson

Explanation: Some 60 million light-years away in the southerly constellation Corvus, two large galaxies are colliding. Stars in the two galaxies, cataloged as NGC 4038 and NGC 4039, very rarely collide in the course of the ponderous cataclysm that lasts for hundreds of millions of years. But the galaxies' large clouds of molecular gas and dust often do, triggering furious episodes of star formation near the center of the cosmic wreckage. Spanning over 500 thousand light-years, this stunning view also reveals new star clusters and matter flung far from the scene of the accident by gravitational tidal forces. The remarkably sharp ground-based image, an accumulation of 88 hours of exposure captured during 2012-2021, follows the faint tidal tails and distant background galaxies in the field of view. The suggestive overall visual appearance of the extended arcing structures gives the galaxy pair, also known as Arp 244, its popular name - The Antennae.

ASTRONOMY - Venus and Mars: Passing in the Night

 2022 March 29

Venus and Mars: Passing in the Night
Image Credit & Copyright: Carlos Kiko Fairbairn

Explanation: When two planets pass on the night sky, they can usually be seen near each other for a week or more. In the case of this planetary conjunction, Venus and Mars passed within 4 degrees of each other earlier this month. The featured image was taken a few days prior, when Venus was slowing rising in the pre-dawn sky, night by night, while Mars was slowly setting. The image, a four-part mosaic, was captured in Brazil from the small town Teresópolis. Besides Venus and Mars, the morning sky now also includes the more distant planet Saturn. Of course, these conjunctions are only angular -- Venus, Mars, and Saturn continue to orbit the Sun in very different parts of our Solar System. Next week, the angle between Saturn and Mars will drop to below a quarter of a degree.

ASTRONOMY - Gems of a Maldivean Night

 2022 March 28

Gems of a Maldivean Night
Image Credit & Copyright: Petr Horálek (ESO Photo Ambassador, Inst. of Physics in Opava)

Explanation: The southernmost part of the Milky Way contains not only the stars of the Southern Cross, but the closest star system to our Sun -- Alpha Centauri. The Southern Cross itself is topped by the bright, yellowish star Gamma Crucis. A line from Gamma Crucis through the blue star at the bottom of the cross, Acrux, points toward the south celestial pole, located just above the small island in the featured picture -- taken in early March. That island is Madivaru of the Maldives in the Indian Ocean. Against faint Milky Way starlight, the dark Coal Sack Nebula lies just left of the cross, while farther left along the Milky Way are the bright stars Alpha Centauri (left) and Beta Centauri (Hadar). Alpha Centauri A, a Sun-like star anchoring a three-star system with exoplanets, is a mere 4.3 light-years distant. Seen from Alpha Centauri, our own Sun would be a bright yellowish star in the otherwise recognizable constellation Cassiopeia.

ASTRONOMY - Titan seas refect sunlight

 2022 March 27

Titan Seas Reflect Sunlight
Image Credit: NASA, JPL-Caltech, U. Arizona, U. Idaho

Explanation: Why would the surface of Titan light up with a blinding flash? The reason: a sunglint from liquid seas. Saturn's moon Titan has numerous smooth lakes of methane that, when the angle is right, reflect sunlight as if they were mirrors. Pictured here in false-color, the robotic Cassini spacecraft that orbited Saturn from 2004 to 2017 imaged the cloud-covered Titan in 2014 in different bands of cloud-piercing infrared light. This specular reflection was so bright it saturated one of Cassini's infrared cameras. Although the sunglint was annoying -- it was also useful. The reflecting regions confirm that northern Titan houses a wide and complex array of seas with a geometry that indicates periods of significant evaporation. During its numerous passes of our Solar System's most mysterious moon, Cassini has revealed Titan to be a world with active weather -- including times when it rains a liquefied version of natural gas.

PHOTOMICROGRAPH - Teresa Zgoda - Fluorescent turtle embryo

Fluorescent turtle embryo